Error detection device and error detection method

ABSTRACT

The state transition condition can be adjusted flexibly and easily while taking advantage of the handshake-type technique. A state transition setting screen 11 of an entire state transition flow including a name 12 of each state based on a communication standard and a state transition condition 13 to be executed between states is displayed on a display screen 6a, and input setting for the state transition condition is possible on the state transition setting screen 11.

TECHNICAL FIELD

The present invention relates to an error detection device and an errordetection method for transmitting a test signal of a known pattern to adevice under test, in a state where the device under test istransitioned to a signal return state by handshake based on acommunication standard of the device under test, and detecting an errorin input data that is returned and received from the device under testin response to the transmission of the test signal.

BACKGROUND ART

For example, in the communication standards of High Speed Serial Bussuch as PCI Express and Universal Serial Bus (USB), when testing areceiver as a device under test, a technique for executing handshakethat transitions the receiver to a test-only signal return state(Loopback.Active), inputting a known pattern for testing, and checkingthe error rate of the returned signal is commonly used.

Incidentally, when the device under test transitions to the signalreturn state (Loopback.Active), two techniques are known: (1) afixed-sequence type technique in which a device under test undergoesstate transition by transmitting a fixed sequence; and (2) a handshaketype technique in which the signal of the device under test is analyzed,handshake based on the actual high-speed serial bus standard performed,and state transition is performed.

As the handshake-type technique (2) related to the present invention,for example, as disclosed in Patent Document 1 below, a technique isknown in which a training pattern generated by an instruction from alink state management unit is transmitted to the device under test, andthe link state of Link Training & Status State Machine (LTSSM) of thedevice under test is transitioned to the signal return state(Loopback.Active).

Here, the fixed-sequence type technique (1) has an advantage that itallows the user to select any combination of patterns and adjusts thetransmission time of each pattern in the fixed sequence, therebyperforming flexible debugging even for devices under test beingdeveloped that cannot operate completely according to the communicationstandard. However, the fixed-sequence type technique (1) requires fineadjustment of the transmission time of the fixed sequence whilecapturing the waveform for each device under test, and this adjustmentrequires a considerable amount of time, which is a disadvantage.

On the other hand, the handshake type technique (2) has an advantagethat it can be used stably and mainly for a device under test that canguarantee the operation according to the communication standard, and thedevice under test can be transitioned to the signal return state(Loopback.Active) without fine adjustment of the transmission time as inthe fixed-sequence type technique (1).

RELATED ART DOCUMENT Patent Document

[Patent Document 1] JP-A-2017-098615

DISCLOSURE OF THE INVENTION Problem that the Invention is to Solve

However, the handshake-type technique (2) has a problem that there arefew setting items, the device under test can only be operated accordingto the communication standard, and the user cannot adjust the statetransition conditions when the handshake fails. This is mainly a problemwhen testing devices under test being developed. In other words, thefinal product of the device under test needs to operate in compliancewith the communication standard, but during development and duringdebugging, there is a demand for flexible state transitions of thedevice under test by having an adjustment width for the state transitioncondition on the error detection device side, but this cannot beachieved by the handshake type technique (2), which is a problem.

Therefore, the present invention has been made in view of the aboveproblems, and provides an error detection device and an error detectionmethod capable of flexibly and easily adjusting state transitionconditions while taking advantage of the handshake-type technique.

Means for Solving the Problem

In order to achieve the above object, an error detection deviceaccording to claim 1 of the present invention is an error detectiondevice 1 that transmits a test signal of a known pattern to a deviceunder test W, in a state where the device under test is transitioned toa signal return state by handshake based on a communication standard ofthe device under test, and detects an error in input data that isreturned and received from the device under test in response to thetransmission of the test signal, the error detection device including:

an operation display unit 6 that displays a state transition settingscreen 11 of an entire state transition flow including each state 12based on the communication standard and a state transition condition 13to be executed between states; and

input and setting for the state transition condition is possible on thestate transition setting screen.

The error detection device according to claim 2 of the present inventionis the error detection device according to claim 1, in which

a state transition condition input box (13 a) on the state transitionsetting screen is able to be input and set within a predeterminedadjustment width including a value defined by the communicationstandard.

The error detection device according to claim 3 of the present inventionis the error detection device according to claim 2, in which

a state transition condition 13D that does not exist in thecommunication standard between states of the state transition settingscreen 11 is able to be selected and set.

The error detection device according to claim 4 of the present inventionis the error detection device according to claim 2, in which

“0” is able to be input and set in the input box of the state transitioncondition (13A) of the transmission state or the state transitioncondition (13B) of the reception state.

The error detection device according to claim 5 of the present inventionis the error detection device according to claim 2, in which

a state transition condition (13D) that does not exist in thecommunication standard between states is able to be selected and set, onthe state transition setting screen.

An error detection method described in claim 6 of the present inventionis an error detection method for transmitting a test signal of a knownpattern to a device under test W, in a state where the device under testis transitioned to a signal return state by handshake based on acommunication standard of the device under test, and detecting an errorin input data that is returned and received from the device under testin response to the transmission of the test signal, the error detectionmethod including:

a step of displaying a state transition setting screen 11 of an entirestate transition flow including each state 12 based on the communicationstandard and a state transition condition 13 to be executed betweenstates; and

a step of inputting and setting the state transition condition on thestate transition setting screen.

The error detection method according to claim 7 of the present inventionis the error detection method according to claim 6, in which

a state transition condition input box (13 a) on the state transitionsetting screen is able to be input and set within a predeterminedadjustment width including a value defined by the communicationstandard.

The error detection method according to claim 8 of the present inventionis the error detection method according to claim 7, in which

a step of controlling a state transition condition 13D that does notexist in the communication standard between states of the statetransition setting screen 11 to be able to be selected and set.

The error detection method according to claim 9 of the present inventionis the error detection method according to claim 7, in which

“0” is able to be input and set in the input box of the state transitioncondition (13A) of the transmission state or the state transitioncondition (13B) of the reception state.

The error detection method according to claim 10 of the presentinvention is the error detection method according to claim 7, in which

a state transition condition (13D) that does not exist in thecommunication standard between states is able to be selected and set, onthe state transition setting screen.

Advantage of the Invention

According to the present invention, it is possible to implement aflexible and easy standard test that has the advantages of both thefixed-sequence type and the handshake type. As a result, the user canaccurately grasp the tendency of the state transition and thecharacteristics of the failure of the device under test, and can performsmooth development and debugging.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block configuration diagram of an error detection deviceaccording to the present invention.

FIG. 2 is a diagram showing an example of a state transition settingscreen of the error detection device according to the present invention.

FIG. 3 is a diagram showing another example of a state transitionsetting screen of the error detection device according to the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment for carrying out the present invention willbe described in detail with reference to the attached drawings.

The present invention relates to an error detection device and an errordetection method using a handshake type technique in which a deviceequipped with a Link Training & Status State Machine (LTSSM) as a linkstate management mechanism that manages the link state, for example, inthe communication standards for High Speed Serial Bus such as PCIExpress, and USB is used as a device under test, and the device undertest is transitioned to a signal return state (Loopback.Active) byhandshake based on the communication standard of the device under test.Note that the LTSSM exists in the physical layer, and transitions basedon the signal received by the physical layer.

Then, in the error detection device and the error detection methodaccording to the present invention, a test signal having a known patternis transmitted to the device under test during the measurement mode inwhich the transition is made to the signal return state(Loopback.Active), and bit errors in the input data that is returned andreceived from the device under test in response to the transmission ofthe test signal is detected.

The device under test W to be detected by the error detection device 1of the present embodiment is equipped with an LTSSM (Wa) that managesthe link state, is connected to the error detection device 1 via a testjig (not shown), during a training mode in which handshake based on thecommunication standard before error detection (before error measurement)is performed, and this connection is detected to start transmission of aLow Frequency Periodic Signaling (LFPS) signal.

Since the interface of the signal output unit of the error detectiondevice 1 and the interface of the signal reception unit of the deviceunder test W are different, a test jig (not shown) is used forconversion for matching these interfaces.

As shown in FIG. 1 , the error detection device 1 of the presentembodiment is generally configured to include a pattern generation unit2, a pattern detection unit 3, an error detection unit 4, a link statemanagement unit 5, an operation display unit 6, a storage unit 7, and acontrol unit 8.

The pattern generation unit 2 generates a pattern to be transmitted tothe device under test W. During the training mode for transitioning theLTSSM (Wa) of the device under test W to the signal return state(Loopback. Active), the pattern generation unit 2 generates a trainingpattern signal corresponding to the link state of the LTSSM under thecontrol by the control unit 8 via the link state management unit 5.

During the measurement mode in which a jitter tolerance test of thedevice under test W is performed in the state where the device undertest W is transitioned to the signal return state (Loopback. Active),the pattern generation unit 2 generates a known pattern signal to beinput to the device under test W, under the control by the control unit8 via the link state management unit 5. The known pattern signal at thistime is, for example, a pseudo-random binary signal sequence of NonReturn to Zero (NRZ) signals of “0” and “1”, and is a Compliance pattern(CP) of a pattern defined by the communication standard.

During the training mode, the pattern detection unit 3 detects thetraining pattern signal transmitted from the device under test Waccording to the state transition of the LTSSM (Wa) of the device undertest W according to the handshake by the training pattern signaltransmitted from the pattern generation unit 2.

When the pattern signal generated by the pattern generation unit 2 isinput to the device under test W during the measurement mode in thestate where the device under test W is transitioned to the signal returnstate (Loopback. Active), along with this, the pattern detection unit 3detects the pattern signal that is returned from the device under test Wto be input.

During the measurement mode, the error detection unit 4 detects the biterror by comparing a known pattern signal generated as a test signal bythe pattern generation unit 2 and a pattern signal that is returned fromthe device under test W and detected by the pattern detection unit 3 inresponse to the transmission of the known pattern signal.

The link state management unit 5 includes an LTSSM having the same orequivalent mechanism as the LTSSM (Wa) mounted on the device under testW, and operates according to the communication standard of the I/Ointerface to be used (for example, USB3.2 Gen1, USB3.2 Gen2, or thelike).

The link state management unit 5 causes the state of the link state totransition to the same state as the LTSSM (Wa) of the device under testW, based on the signals communicated with the device under test W, andcan recognize the current link state of the LTSSM (Wa) in the deviceunder test W. Thus, it is possible to obtain various types ofinformation such as an LTSSM value, a link speed, presence or absence ofloopback, an LTSSM transition pattern, a lane number for identifying thelane, a link number, a generation time and the number of generations ofa pattern signal, an emphasis amount, and an adjustment value of anequalizer on the receiving side.

The operation display unit 6 is a user interface including a displayunit such as a liquid crystal display, and an operation unit such asvarious keys, switches, buttons, and soft keys on the display screen ofthe display unit provided in the error detection device 1, and isoperated when performing various settings and displays related to errordetection.

Specifically, the operation display unit 6 displays a setting screenrelated to error detection, log information stored in the storage unit7, and measurement results including error information detected by theerror detection unit 15, under the control of the control unit 8 basedon the operation of the operation unit.

In addition, the operation display unit 6 displays the state transitionsetting screen 11 in the display forms shown in FIGS. 2 and 3 on thedisplay screen 6a, as a display related to the state transition due tohandshake with the device under test W, under the control of the controlunit 8 based on the operation of the operation unit.

The state transition setting screen 11 graphically displays, on thedisplay screen, the entire state transition flow including each state(an elliptical portion displaying the name of each state) 12 based onthe communication standard, and a state transition condition (arectangular portion displaying the state transition condition) 13executed between states.

Here, FIG. 2 shows a state transition setting screen 11 of USB3.2 Gen1.On the state transition setting screen 11 of FIG. 2 , from the top tothe bottom of the screen, each state 12 is displayed in the statetransition order of “Rx. Detect”→“Polling.LFPS”→“Polling.RxEQ”→“Polling.Active”→“Polling.Configuration”→“Polling.Idle”→“Loopback.Active”.

FIG. 3 shows the state transition setting screen 11 of USB3.2 Gen2. Onthe state transition setting screen 11 of FIG. 3 , from the top to thebottom of the screen, each state 12 is displayed in the state transitionorder of “Rx. Detect”→“Polling.LFPS”→“Polling.LFPS Plus”→“Polling.PortMatch”→“Polling.PortConfiguration”→“Polling.RxEQ”→“Polling.Active”→“Polling.Configuration”→“Polling.Idle”→“Loopback.Active”.

Further, on the state transition setting screen 11 of FIG. 2 or FIG. 3 ,the state transition condition 13A of the transmission state (PPGCondition) is displayed on the left side of each state 12 as the statetransition condition 13 executed between states, the state transitioncondition 13B of the reception state (ED Condition) is displayed on theleft side thereof, and the state transition condition 13C of TimeoutSetting [ms] is displayed on the right side of each state 12.

Specifically, in the state transition setting screen 11 of FIG. 2 , thestate transition condition 13A of the transmission state corresponds to“Sent [16] bursts LFPS”, “Sent [4] bursts LFPS”, and “Sent [65,536]TSEQ”, “Sent [16] TS1 OS” and “Sent [16] TS2 OS”. The state transitioncondition 13B of the reception state corresponds to “Received DUT'sLFPS”, “Received [2] LFPS”, “Received [8] TS1/TS2 OS”, and “Received [8]TS2 OS”. The state transition condition 13C of the timeout settingcorresponds to [360], [12.0], [12.0], [2.0], and [2.0] between each of“Polling.LFPS”, “Polling.RxEQ”, “Polling. Active”, “Polling.Configuration”, and “Polling.Idle” and “Rx.Detect”.

Further, on the state transition setting screen 11 of FIG. 3 , the statetransition condition 13A of transmission state corresponds to “Sent [2]SCD1”, “Sent [2] SCD2”, “Sent [4] PHY Cap.LBPM”, “Sent [4] PHY ReadyLBPM”, “Sent [524, 288] TSEQ”, “Sent [16] TS1 OS”, and “Sent [16] TS2OS”. The state transition condition 13B of reception state correspondsto “Received DUT's LFPS”, “Received [1] SCD1/SCD2”, “Received [1] SCD2”,“Received [2] LBPM”, “Received [2] PHY Ready LBPM”, “Received [8]TS1/TS2 OS”, and “Received [8] TS2 OS”. The state transition condition13C of timeout setting corresponds to [360], [360], [12.0], [12.0],[12.0], [12.0], and [2.0] between “Polling.LFPS”, “Polling.LFPS Plus”,“Polling.Port Match”, “Polling.Port Configuration”, “Polling.RxEQ”,“Polling.Active”, “Polling.Configuration”, and “Polling.Idle” and“Rx.Detect”.

[ ] of each of the state transition condition 13A of the transmissionstate, the state transition condition 13B of the reception state, andthe state transition condition 13C of the timeout setting corresponds tothe input box 13 a described below, and the number in the [ ] indicatesa value to be set and input in the input box 13 a.

The state transition condition 13 (the state transition condition 13A ofthe transmission state, the state transition condition 13B of thereception state, and the state transition condition 13C of the timeoutsetting) in FIG. 2 or FIG. 3 are configured such that variable inputsetting is possible with a predetermined adjustment width including avalue defined by the communication standard for each input box 13 a.Thus, it is possible to perform more detailed input settings withoutbeing limited to fixed values defined by the communication standards.

For example, on the state transition setting screen 11 of FIG. 2 or FIG.3 , the state transition condition 13B of the reception state: “Received[8] TS1/TS2 OS” means the condition of transitioning to the next stateafter receiving TS1 or TS2 eight times consecutively in a state of“Polling.Active”, but the user can input and set, in the input box 13 a,for example, any value within the range of “0 to 65535”, including thevalue “8” currently input in the input box 13 a as a value defined bythe communication standard.

Further, when “0” is input and set in the input box 13 a of the statetransition condition 13A of the transmission state and the statetransition condition 13B of the reception state, as 0 setting, it ispossible to skip the state transition condition and transition to thenext state transition condition or the next state. Thus, even when thehandshake with the device under test W fails, the subsequent statetransition conditions, including the failed state transition condition,are set to 0, so that it is possible to quickly make transition to“Loopback.Active” state.

When performing handshake with the device under test W, a value definedby the communication standard of the device under test W, or a valuewhen handshake with the device under test W is finally performed is setas the initial value in the input box 13 a of each state transitioncondition 13.

On the state transition setting screen 11, a state transition condition13D that does not exist in the communication standard between states canbe selected and set. For example, on the state transition setting screen11 of FIGS. 2 and 3 , in the state of “Polling.Active”, the statetransition condition 13A of the transmission state after receiving TS1or TS2 eight times consecutively: “Sent [16] TS1 OS” corresponds to thestate transition condition 13D that does not exist in the communicationstandard. A check box 13 b is provided for the state transitioncondition 13D that does not exist in this communication standard, andswitching between valid and invalid is performed depending on whether ornot the check box 13 b is checked. Thus, by setting and inputting adesired value in the input box 13 a with the check box 13 b of the statetransition condition 13D that does not exist in the communicationstandard described above being checked, the time in the “Polling.Active”state can be extended, and timing adjustment can be performed.

Note that on the state transition setting screen 11 of FIG. 2 or 3 ,“Transition Delay [1] ms” is added as the state transition condition 13Dthat does not exist in the communication standard between the statetransition condition of a reception state: “Received DUT's LFPS” and thestate: “Polling.LFPS”, but the adding position is not limited thereto.The state transition condition 13D that does not exist in thiscommunication standard can be appropriately added to a portion wherethere is a state whose timing is difficult to adjust for eachcommunication standard.

Under the control of the control unit 8, the storage unit 7 stores, forexample, the link state transition destination, transition occurrencetime, transition trigger, error information, or the like, managed by thelink state management unit 5, as log information according to thetransition state of the LTSSM.

The control unit 8 integrally controls respective units (the link statemanagement unit 5, the operation display unit 6, and the storage unit7), when performing handshake with the device under test W and errordetection.

Specifically, during the training mode, the control unit 8 instructs thepattern generation unit 2 via the link state management unit 5 togenerate a training pattern signal to be generated next according to thecurrent link state of the LTSSM of the link state management unit 5.

The control unit 8 also instructs the pattern generation unit 2 via thelink state management unit 5 to generate a pattern signal, during themeasurement mode.

Further, the control unit 8 includes display control means 8 a forcontrolling the reading of the log information corresponding to thetransition state of the LTSSM of the link state management unit 5 andthe detection result of the error detection unit 4, performing displaycontrol of the read log information and detection result to theoperation display unit 6, and performing display control of the statetransition setting screen 11 shown in FIGS. 2 and 3 .

When the handshake is performed between the error detection device 1 andthe device under test W configured as described above, the errordetection device 1 and the device under test W are connected via a testjig (not shown).

When the connection to the error detection device 1 via the test jig isdetected, the device under test W starts the transmission of the LFPSsignal as a training pattern signal.

When receiving the LFPS signal transmitted from the device under test W,the error detection device 1 transitions to the Polling.LFPS state andstarts transmitting the LFPS signal as a training pattern signal.

When the LFPS signal transmitted from the error detection device 1 isreceived, the device under test W transitions to the next state, andtransmits a training pattern signal corresponding to the next state.

Then, when the handshake between the device under test W and the errordetection device 1 is successful, the device under test W and the errordetection device 1 transmit training pattern signals defined in eachstate to each other, the state transitions, and the LTSSM of the deviceunder test W transitions to the Loopback.Active state for the finaltest.

Here, when the handshake between the device under test W and the errordetection device 1 fails and transition to Loopback.Active state is notmade, on the state transition setting screen 11 in FIG. 2 and FIG. 3 ,the value set in the input box 13 a of the state transition condition 13(state transition condition 13A of the transmission state, statetransition condition 13B of the reception state, and state transitioncondition 13C for timeout setting) which may be the cause of the failureof the handshake may be adjusted and the handshake with the device undertest W may be executed again.

Further, when there is a state whose timing is difficult to adjustdepending on the communication standard, it is possible to check thecheck box 13 b of the state transition condition 13D that does not existin the communication standard, and set and input a desired value in theinput box 13 a.

Incidentally, in the above-described embodiment, as shown in FIG. 1 ,the error detection device 1 is configured to integrally include thepattern generation unit 2, the pattern detection unit 3, the errordetection unit 4, the link state management unit 5, the operationdisplay unit 6, the storage unit 7, and the control unit 8, but thepresent invention is not limited to this configuration. For example, theoperation display unit 6 may be configured by an external device such asa personal computer connected to the outside, or the operation displayunit 6 may be configured by separate modules for the operation unit andthe display unit, or the pattern generation unit 2 and the patterndetection unit 3 can be separately modularized or made into individualhousings.

As described above, in the present embodiment, the value to be input inthe input box 13 a of the state transition condition 13 defined by thecommunication standard is not a fixed value but has an adjustment width.Further, the state transition condition 13D that does not exist in thecommunication standard can be selectively added by checking the checkbox 13 b on the state transition setting screen 11. This makes itpossible to implement a flexible and easy standard test that has theadvantages of both the fixed-sequence type and the handshake type. As aresult, the user can accurately grasp the tendency of the statetransition and the characteristics of the failure of the device undertest, and can perform smooth development and debugging.

Although the best form of the error detection device and the errordetection method according to the present invention has been describedabove, the present invention is not limited by the description anddrawings in this form. That is, it goes without saying that all otherforms, examples, operational techniques, and the like made by thoseskilled in the art based on this form are included in the scope of thepresent invention.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

1 Error detection device

2 Pattern generation unit

3 Pattern detection unit

4 Error detection unit

5 Link state management unit

6 Operation display unit

7 Storage unit

8 Control unit

8 a Display control means

11 State transition setting screen

12 State (state name)

13 State transition condition

13A State transition condition of transmission state

13B State transition condition of reception state

13C State transition condition of timeout setting

13D State transition condition that does not exist in communicationstandard

13 a Input box

13 b Checkbox

W Device under test

Wa LTSSM

What is claimed is:
 1. An error detection device that transmits a testsignal of a known pattern to a device under test, in a state where thedevice under test is transitioned to a signal return state by handshakebased on a communication standard of the device under test, and detectsan error in input data that is returned and received from the deviceunder test in response to the transmission of the test signal, the errordetection device comprising: an operation display unit that displays astate transition setting screen of an entire state transition flowincluding each state based on the communication standard and a statetransition condition to be executed between states, wherein input andsetting for the state transition condition is possible on the statetransition setting screen.
 2. The error detection device according toclaim 1, wherein an input box of the state transition condition on thestate transition setting screen is able to be input and set within apredetermined adjustment width including a value defined by thecommunication standard.
 3. The error detection device according to claim2, wherein a state transition condition that does not exist in thecommunication standard between states on the state transition settingscreen is able to be selected and set.
 4. The error detection deviceaccording to claim 2, wherein “0” is able to be input and set in theinput box of a state transition condition of a transmission state or astate transition condition of a reception state.
 5. The error detectiondevice according to claim 2, wherein a state transition condition thatdoes not exist in the communication standard between states is able tobe selected and set, on the state transition setting screen.
 6. An errordetection method for transmitting a test signal of a known pattern to adevice under test, in a state where the device under test istransitioned to a signal return state by handshake based on acommunication standard of the device under test, and detecting an errorin input data that is returned and received from the device under testin response to the transmission of the test signal, the error detectionmethod comprising: a step of displaying a state transition settingscreen of an entire state transition flow including each state based onthe communication standard and a state transition condition to beexecuted between states; and a step of inputting and setting the statetransition condition on the state transition setting screen.
 7. Theerror detection method according to claim 6, wherein a state transitioncondition input box on the state transition setting screen is able to beinput and set within a predetermined adjustment width including a valuedefined by the communication standard.
 8. The error detection methodaccording to claim 7, further comprising: a step of controlling a statetransition condition that does not exist in the communication standardbetween states on the state transition setting screen to be able to beselected and set.
 9. The error detection method according to claim 7,wherein “0” is able to be input and set in the input box of a statetransition condition of a transmission state or a state transitioncondition of a reception state.
 10. The error detection method accordingto claim 7, wherein a state transition condition that does not exist inthe communication standard between states is able to be selected andset, on the state transition setting screen.